Charles a



Filed April 29 1920 C. A. CADWELLY ELECTRIC FURNAQE 2 Sheets-Sheet l Aug. 14 1923.

C: A. CADWELL ELECTRIC FURNACE 2 sheets-'sheen 2 Filed April 29 1920 afro: ucm) l tion of principal interest in the present furnace is the muflle chamber 15 inv which, as previously indicated, the articles or objects to be heated are placed. Chamber 1.5, as best shown in Fig-2, is of general elliptical cross-section and extends transversely of the furnace chamber proper between the two electrodes 8, its respective side walls just clearing the latter, and its bottom and top similarly just clearing the resistor 10 and the cover of the furnace chamber. The

respective ends of said chamber are imotherend of the chamber 15 may be eXtend` ed through the furnace wall and be provided with a similar plug so as to permit access from both ends. The walls of chamber 15 are preferably of composite construction, consisting of a plurality of carbon reenforcing rods 17 plastered over, so as te be completely imbedded on all sides, with a Y layer 18 of carborundum. In addition, vthe interior of the chamber may be lined with a coating 19 of alundum cement or other highly resistant coating that will withstand exposure to the air, as well as the wear incident to the purpose for which themulile is used. As shown in Figs. 3 and 4, thecarbon rods or pencils 17 are the only parts of the mullle chamber that extend into the side walls of the furnace chamber proper, said rods thus constituting the means of support for the mulile chamber and reenforcing the latter so as to prevent sagging and cracking under the inte-nse heat to 'which it is subjected. Y

In operation, assuming the electrodes 8 to be connected in an electric circuit of proper voltage Vand amperage, said elctrodes are adjusted to cause an arcv to form between the respective lower Vends* thereof and the plates 11. The heat of said arcs will obviously be directedinwardly towards Athe side walls of the muflle chamber 15, while the heat developed by the passage of the current through the resistor 10 will similarly be directed against the under wall of said cham ber. The end walls of the furnace chamber,

as well as the coverthereof, will reflect andl within the furnace chamber to best advan;

tage.

@ther modes of applying the principle vof my invention may be employed instead of the one explained, change being. made 'as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention 1. In an electric furnace, the combination of an elongate furnace chamber; electrodes extending downwardly into such chamber oneat each end; a resistor within said chamber lying on the floor thereof between said electrodes; and a muille chamber supported atits ends in the respective side walls. of said furnace chamber so as to lie over said resistor and between said electrodes.

9,. In an electric furnace, the combination of an elongate furnace chamber; electrodes extending downwardly into such chamber one at each end; a resistor within said chamber lying on the floor thereof `between said electrodes; and a muflie chamber supported at its endsin the respective side walls of said furnace chamber so as to lie over said resistor and between said electrodes, said muffle chamber` being of curved cross-'secf tion.

3. In anelectric furnace, the combination of an elongate furnaceichamber; electrodes extending downwardly into such chamber one at each end; a resistor within said cham` ber lying'on the floor thereof between said electrodes; and a Vmufile chambersupported at its ends -inhthe respective side walls of said furnace chamber so as to lie over said resistor and between said electrodes, said muflle chamber being ellipticalv in cross-Section.

4. In an electric furnace, the combination of anY elongate furnace chamber; electrodesex'tending ldownwardly into such lchamber one at eac-h end; a resistor within said chamber lying on the floor thereof between said electrodes; and a muflie chamber supported at its ends in the respective side walls of said furnace chamber so as to lie over said resistor Y and between' said electrodes, said mulile chamber being composed of a plurality of `carbon rods plastered over with a layerof lsuitable heat-resistant material.`

5. In an electric furnace, the combination of an elongate furnace chamber; electrodes extending downwardly into such chamber one at each end; a resister within Said chamber lying on the floor thereof between said electrodes; anda muflle chamber supported at its ends in the respective side walls of said furnace chamber so as to lie over said resistor and between said electrodes, said mufliechamber being composed of a plurality of carbon rods plastered over with a layer of carborundum.

6.. In an Velectric furnace, the combination of an elongate furnacechamber; electrodes 1,404,496 Y Y Y Y l -3 extending downwardly into such chamber muie chamber being composed ofaplurality oneat each end; a resistor Within said chamof carbon rods plastered over` with a layer berV lying on the ioor thereof between said of carborundum and being lined with Wear- 10 electrodes; and aV Inutile chamber supported resistant material not affected by Contact 5 at its ends in the respective side Walls of with the air.

said furnace chamber so as to lie over said Signed by me this 24 day of A ril, 1920. Y resistor and between said electrodes, said CHARLES A. CAD ELL.V 

